The proposed research is designed to test hypotheses about the function of horns and to apply results to the conservation of asocial megavertebrates, particularly in response to catastrophic reductions due to poaching. To delay the decline, a bold experiment is being attempted in Namibia where male and female black rhinos have been dehorned. Unlike actions employed in other geographic regions, dehorning has been controversial for three principal reasons: (1) while horns are re-grown, rates of re-growth remain unknown making it impossible to know where horn removal might be needed again; (2) because not all animals are dehorned, horned animals may have reproductive advantages; hence, effects of removal on the breeding and genetic structure of the population are unclear; and (3) the calves of hornless females may be more vulnerable to predation. In the absence of information, horn function cannot be assessed. The proposed research addresses these issues by gathering data on horn growth and regrowth, comparing reproduction among rhinos varying in horn size, and examining the frequency of attacks by predators toward, and responses of, horned and hornless rhinos. Two study sites will be used, one with horned and hornless rhinos, and another with individuals all with intact horns. The research promises new insight into the effects of anatomical structures on life histories of animals in the wild, and has significant potential for affecting management of this rare species.
